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Android Openweathermap API: JSON, HTTP

android_develop_weather_app_tutorial

This post describes how to use android Openweathermap api to build android weather app that gives current weather information. This android app will use JSON, HTTP connection and AsyncTask to get this information.. As weather provider I will use OpenWeatherMap a free weather service that provides some interesting API really easy to use.I will guide you through the steps necessary to build up a working android weather app. For more information about API, you can visit the OpenWeatherMap web site.

You check this tutorial to  know how to retrieve current user position and the corresponding city name.

How to develop Android Weather app tutorial

I will show to you the final result so you can have an idea about what we will do in this post.

android openweathermap api

Openweathermap API requires to use API Key that has to be added to the request, like:

http://api.openweathermap.org/......&APPID={API_KEY}

In the tutorial below we assume you have the API Key and you append it to the url. You can obtain it for free
after creating your account.

Android Openweathermap API: Current weather info

OpenWeatherMap offers several API to use to get weather information. We want to use the one that gives us the current weather info. The URL to call to get this info is:
http://api.openweathermap.org/data/2.5/weather?q=city,country

Let’s suppose we want to know the weather in Rome, IT. Using our browser we can have:

weather_api_search
As we can see we have JSON response. Formatting the response we have

{
"coord":{"lon":12.4958,"lat":41.903},
"sys":{"country":"Italy","sunrise":1369107818,"sunset":1369160979},
"weather":[{
"id":802,"main":"Clouds","description":"scattered clouds",
"icon":"03d"}],
"base":"global stations",
"main":{
"temp":290.38,
"humidity":68,
"pressure":1015,
"temp_min":287.04,
"temp_max":293.71},
"wind":{
"speed":1.75,
"deg":290.002},
"clouds":{"all":32},
"dt":1369122932,
"id":3169070,
"name":"Rome",
"cod":200
}

So the first thing we need to do is creating our data model so that we can parse the response and convert it into Java classes. Analyzing the response we have different “main” tags that we can use as class in Java:

  • coord (object)
  • sys (object)
  • weather (array)
  • main (object)
  • wind (object)
  • name: (String)

The response is quite simple and we can convert it manually. The UML class diagram for the model is shown below:

 

openweathermap class diagram

 

Android JSON Weather Parser

Once we have created our model we have to parse it. We can create a specific class that handles this task. First we have to create the “root” object that receive as input the entire string containing all the JSON response:

// We create out JSONObject from the data
JSONObject jObj = new JSONObject(data);

Then we start parsing each piece of the response:

// We start extracting the info
Location loc = new Location();

JSONObject coordObj = getObject("coord", jObj);
loc.setLatitude(getFloat("lat", coordObj));
loc.setLongitude(getFloat("lon", coordObj));

JSONObject sysObj = getObject("sys", jObj);
loc.setCountry(getString("country", sysObj));
loc.setSunrise(getInt("sunrise", sysObj));
loc.setSunset(getInt("sunset", sysObj));
loc.setCity(getString("name", jObj));
weather.location = loc;

In the line 4,8 we create two “sub” object (coordObj and sysObj) having as parent the jObj as it clear from the JSON response. As we can see we use some helper methods to get String,int and float values:

private static JSONObject getObject(String tagName, JSONObject jObj) throws JSONException {
JSONObject subObj = jObj.getJSONObject(tagName);
return subObj;
}

private static String getString(String tagName, JSONObject jObj) throws JSONException {
return jObj.getString(tagName);
}

private static float getFloat(String tagName, JSONObject jObj) throws JSONException {
return (float) jObj.getDouble(tagName);
}

private static int getInt(String tagName, JSONObject jObj) throws JSONException {
return jObj.getInt(tagName);
}

And then we finally parse the weather information. We have to remember that weather tag is an array so we have to handle it differently

// We get weather info (This is an array)
JSONArray jArr = jObj.getJSONArray("weather");

// We use only the first value
JSONObject JSONWeather = jArr.getJSONObject(0);
weather.currentCondition.setWeatherId(getInt("id", JSONWeather));
weather.currentCondition.setDescr(getString("description", JSONWeather));
weather.currentCondition.setCondition(getString("main", JSONWeather));
weather.currentCondition.setIcon(getString("icon", JSONWeather));

JSONObject mainObj = getObject("main", jObj);
weather.currentCondition.setHumidity(getInt("humidity", mainObj));
weather.currentCondition.setPressure(getInt("pressure", mainObj));
weather.temperature.setMaxTemp(getFloat("temp_max", mainObj));
weather.temperature.setMinTemp(getFloat("temp_min", mainObj));
weather.temperature.setTemp(getFloat("temp", mainObj));

// Wind
JSONObject wObj = getObject("wind", jObj);
weather.wind.setSpeed(getFloat("speed", wObj));
weather.wind.setDeg(getFloat("deg", wObj));

// Clouds
JSONObject cObj = getObject("clouds", jObj);
weather.clouds.setPerc(getInt("all", cObj));

At the end we have our Weather class filled with the data retrieved.

Android HTTP Request and Response

Now we have to exchange information between our android app and the remote server using HTTP protocol so that the app invokes Android Openweathermap API. We have to send information and then read the response. We covered this topic in the previous post(Android HTTP Client: GET, POST, Download, Upload, Multipart Request) so we won’t describe it again, we simply show the code:

public class WeatherHttpClient {

private static String BASE_URL = "http://api.openweathermap.org/data/2.5/weather?q=";
private static String IMG_URL = "http://openweathermap.org/img/w/";

public String getWeatherData(String location) {
HttpURLConnection con = null ;
InputStream is = null;

try {
con = (HttpURLConnection) ( new URL(BASE_URL + location)).openConnection();
con.setRequestMethod("GET");
con.setDoInput(true);
con.setDoOutput(true);
con.connect();

// Let's read the response
StringBuffer buffer = new StringBuffer();
is = con.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line = null;
while ( (line = br.readLine()) != null )
buffer.append(line + "rn");

is.close();
con.disconnect();
return buffer.toString();
}
catch(Throwable t) {
t.printStackTrace();
}
finally {
try { is.close(); } catch(Throwable t) {}
try { con.disconnect(); } catch(Throwable t) {}
}

return null;

}

public byte[] getImage(String code) {
HttpURLConnection con = null ;
InputStream is = null;
try {
con = (HttpURLConnection) ( new URL(IMG_URL + code)).openConnection();
con.setRequestMethod("GET");
con.setDoInput(true);
con.setDoOutput(true);
con.connect();

// Let's read the response
is = con.getInputStream();
byte[] buffer = new byte[1024];
ByteArrayOutputStream baos = new ByteArrayOutputStream();

while ( is.read(buffer) != -1)
baos.write(buffer);

return baos.toByteArray();
}
catch(Throwable t) {
t.printStackTrace();
}
finally {
try { is.close(); } catch(Throwable t) {}
try { con.disconnect(); } catch(Throwable t) {}
}

return null;

}
}

Android Weather App

Finally, it is the time for our Activity. The layout is very simple and of course it is just a skeleton you need to improve it if you want to have a production app.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<TextView
android:id="@+id/cityText"
style="?android:attr/textAppearanceMedium"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true" />

<ImageView
android:id="@+id/condIcon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/cityText" />

<TextView
android:id="@+id/condDescr"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/condIcon"
android:layout_alignLeft="@id/condIcon"
/>

<TextView
android:id="@+id/temp"
style="@style/tempStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="12dp"
android:layout_alignBaseline="@id/condDescr"
android:layout_toRightOf="@id/condDescr"/>

<TextView
android:id="@+id/pressLab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/condDescr"
android:text="Pressure"
android:layout_marginTop="15dp" />

<TextView
android:id="@+id/press"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/pressLab"
android:layout_toRightOf="@id/pressLab"
style="@style/valData"/>

<TextView
android:id="@+id/humLab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/pressLab"
android:text="Humidity" />

<TextView
android:id="@+id/hum"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/humLab"
android:layout_toRightOf="@id/humLab"
android:layout_marginLeft="4dp"
style="@style/valData"/>

<TextView
android:id="@+id/windLab"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@id/humLab"
android:text="Wind" />

<TextView
android:id="@+id/windSpeed"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/windLab"
android:layout_toRightOf="@id/windLab"
android:layout_marginLeft="4dp"
style="@style/valData" />

<TextView
android:id="@+id/windDeg"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/windLab"
android:layout_toRightOf="@id/windSpeed"
android:layout_marginLeft="4dp"
style="@style/valData"/>

</RelativeLayout>

In onCreate method we simply get the reference to the Views inside the layout so that we can populate them later after the request is completed.

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String city = "Rome,IT";

cityText = (TextView) findViewById(R.id.cityText);
condDescr = (TextView) findViewById(R.id.condDescr);
temp = (TextView) findViewById(R.id.temp);
hum = (TextView) findViewById(R.id.hum);
press = (TextView) findViewById(R.id.press);
windSpeed = (TextView) findViewById(R.id.windSpeed);
windDeg = (TextView) findViewById(R.id.windDeg);
imgView = (ImageView) findViewById(R.id.condIcon);

JSONWeatherTask task = new JSONWeatherTask();
task.execute(new String[]{city});
}

and we start an AsyncTask, because as we already know network operations are time consuming so we can run them in the main thread otherwise we could have an ANR problem. The JSONWeatherTask is very simply

protected Weather doInBackground(String... params) {
Weather weather = new Weather();
String data = ( (new WeatherHttpClient()).getWeatherData(params[0]));

try {
weather = JSONWeatherParser.getWeather(data);

// Let's retrieve the icon
weather.iconData = ( (new WeatherHttpClient()).getImage(weather.currentCondition.getIcon()));

} catch (JSONException e) {
e.printStackTrace();
}
return weather;

}

At line 3 we make the HTTP request and then we parse it at line 6.

At line 9 we retrieve the icon that shows the weather condition.
Running the code we have:

openweathermap current weather api
openweathermap api how to build android app

It could be interesting integrate a physical object using IoT project with weather forecast and Arduino.

The source code available @github.

Recently another post describes how to build location aware app in Android to retrieve UV Index.

I’ve released a new WeatherLib for Android that simplifies the weather app coding helping you in many app details. This lib supports Openweathermap and other weather provider. If you are interested give a look here
You can even join the new community to talk about it.

weatherlib

 

75 comments

  1. Wetzel402 says:

    Thank you for the great tutorials and open source code. It has been a huge help for me in learning parsing.

  2. rogierv says:

    When I enter "JSONObject coordObj = getObject("coord", jObj);" in the mainactivity I get the error: "Unhandled exception: org.json.JSON.exception". While the getObject method is also implemented and org.json.JSONException is imported.

  3. AndroidDev101 says:

    Thanks, great tutorial! Could you tell me how to use the forecast feature as well? For example displaying the 5 day forecast?

  4. survivingwithandroid says:

    I'm planning to write a post about next days forecast. Many people are asking for it.
    Be patient please! Thx

  5. alan123 says:

    Awesome job. How would you change the location though? I'm trying to make a weather app so I want to be able to change the location using the gps. Thanks in advance.

  6. survivingwithandroid says:

    You should get the gps location coord and then make a query using lat and long parameters. Check the openweathermap api for more information

  7. jorge100613 says:

    This tutorial is very helpful, but one problem I have is the weather icon doesn't show up. In the onPostExecute() method the if statement never runs. Do you have any idea why that's happening?

  8. survivingwithandroid says:

    As far as i know, there are some weather code that doesn't have an icon. You should map weather code with your icon weather set.

  9. wolf says:

    I'm using your code exactly and it works great but icons don't show up. I can see the icons in your screenshots, can you give us the code you use?

  10. sathish says:

    Hi, this is a great example, thanks for this.

    I just don't know for what purpose
    " con.setDoInput(true); -> Line 48
    con.setDoOutput(true); -> Line 49"

    these two lines are added, but when i removed these two lines weatherhttpclient, the icon showed up on the app. When these line are used the server is returning File Not Found Exception

  11. sathish says:

    In Main activity i think the conversion to centigrade, needs to be "temp.setText("" + Math.round((weather.temperature.getTemp() – 273.15)) + "°C"); instead of "temp.setText("" + Math.round((weather.temperature.getTemp() – 275.15)) + "°C");

  12. survivingwithandroid says:

    setDoInput means that the app wants to use the connection as input, so it wants to read data. AFAIK the default value is true so if you remove it i guess the result doesn't change. setDoOutput means the app wants to write to the connection. The default value is false. In my experience this two parameters doesn't affect the icon download. If you look at my app in the app store it download icons correctly. Anyway i guess the problem happens when there's some weather code that doesn't match an icon. Let me know if you have an example that helps me.

  13. Priya says:

    Great Tutorial Thanks! I was trying your example and I am getting an error while downloading the weather icons. I get the following exception

    12-19 00:15:39.049: W/System.err(1295): java.io.FileNotFoundException: http://openweathermap.org/img/w/01n

    when I type this url in the browser I am able to see the weather icon but in the android emulator this fails. Any idea?

  14. Rushikesh Gomekar says:

    i'm getting null from this method :

    weather.iconData = ( (new WeatherHttpClient()).getImage(weather.currentCondition.getIcon()));

  15. survivingwithandroid says:

    You can create a map between the weather code condition and a resource id related to the icon you want to show.

  16. giupardeb says:

    Ok, but how many types of weather's description are there? for example:

    Clouds, broken clouds, light rain, etc..

  17. davide dellai says:

    Anyone knows why my location is always London instead Vicenza (Italy)? I tried to download the source and run the apk but always returns that i am in London.. Doesn't recognize the geolocation?

  18. survivingwithandroid says:

    In the tutorial source code, the geolocation is not implemented. If you look at line 59 of the MainActivity class you can notice there is:

    String city = "London,UK";

    for that it loads by default London weather condition. Hope it helps you.

  19. davide dellai says:

    Ah ok.. because i really need the code with geolocation and i can't find anything on the web.. I need very little informations like only : condition and temperature nothing more. Of course using location. But actually i can't do it. Can i contact you via hangout?

  20. Steve says:

    How can I create a "iconData" resource reference for new icons? I put in the line:

    if (weather.iconData != null && weather.iconData.length > 0){
    -> here I put the icon reference with if statement, am I right?
    }
    I appreciate any help

  21. JR says:

    I am hoping you can help, I get some user crashes on 4.4.2 on a few devices. Hoping you could point me in the right direction.

    I am using open weather, per your http client

    private static String BASE_URL = "http://api.openweathermap.org/data/2.5/weather?&quot;;

    "message" and "gust" are not part of you tutorial, but I do not get a crash on my devices even they return this. I am not familair with parse outside of your tutorial.

    Line 44

    JSONObject jObj = new JSONObject(data);

    Thanks

    On data, I get the following,

    WEATHER DATA

    {"coord":{"lon":-99.04,"lat":34.17},"sys":{"message":0.037,"country":"US","sunrise":1397218143,"sunset":1397264699},"weather":[{"id":800,"main":"Clear","description":"Sky is Clear","icon":"01n"}],"base":"cmc stations","main":{"temp":292.06,"pressure":1011,"temp_min":291.15,"temp_max":293.15,"humidity":31},"wind":{"speed":3.6,"gust":5.65,"deg":18},"clouds":{"all":0},"dt":1397188520,"id":4716202,"name":"Oklaunion","cod":200}

    java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:300)
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:841)

    Caused by: java.lang.NullPointerException
    at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
    at org.json.JSONTokener.nextValue(JSONTokener.java:94)
    at org.json.JSONObject.(JSONObject.java:155)
    at org.json.JSONObject.(JSONObject.java:172)
    at com.survivingwithandroid.weatherapp.model.JSONWeatherParser.getWeather(JSONWeatherParser.java:44)

  22. JR says:

    My post was cutoff at the bottom

    java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:300)
    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
    at java.util.concurrent.FutureTask.run(FutureTask.java:242)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:841)

    Caused by: java.lang.NullPointerException
    at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
    at org.json.JSONTokener.nextValue(JSONTokener.java:94)
    at org.json.JSONObject.(JSONObject.java:155)
    at org.json.JSONObject.(JSONObject.java:172)
    at com.survivingwithandroid.weatherapp.model.JSONWeatherParser.getWeather(JSONWeatherParser.java:44)
    atnet.RollMeOver.RollMeOver.RollMeOverActivity$JSONWeatherTask.doInBackground(RollMeOverActivity.java:3896)
    at net.RollMeOver.RollMeOver.RollMeOverActivity$JSONWeatherTask.doInBackground(RollMeOverActivity.java:1)
    at android.os.AsyncTask$2.call(AsyncTask.java:288)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
    at java.lang.Thread.run(Thread.java:841)

  23. JR says:

    Line 44 is

    JSONObject jObj = new JSONObject(data);

    The only comment preceding it was
    // We create out JSONObject from the data

    I had a longer first post, (above is second) which I provided more detail, I assume you read and deleted it? Thanks for the quick response.

  24. Prashanth Puranik says:

    Remove the con.setDoOutput(true); statement in getImage(). Not sure exactly why, but it does to trick.

    PS: Without this it gives 405 status code, which means server refused to send data probably due to some headers it didn't expect tosee in request (just a guess). You can read info on error 405 here – http://www.checkupdown.com/status/E405.html

  25. ThemuRR says:

    I seem to be a bit late to the party but when I run the source code (from github) the app stops working immediately.. Any ideas?

  26. ThemuRR says:

    I seem to be a bit late to the party but when I run the source code (from github) the app stops working immediately.. Any ideas?

  27. Juan Ignacio Alvarez says:

    In this line:
    JSONObject jObj = new JSONObject(data);

    What is "data"???? where do you get it from?

  28. surya says:

    Hi,
    I was developing weather application using openweathermap api, before 2months all are working fine, but now for certain city’s i couldn’t able to fetch the response eg for chennai(Using volley- Error code: BasicNetwork.performRequest: Unexpected response code 401 for http://api.openweathermap.org/data/2.5/weather?q=Chennai&appid=44db6a862fba0b067b1930da0d769e98) but it is working fine in browser and postman

    Plz suggest to find out where i am missing out

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